Vaccine might have averted egg recall over salmonella

Low-cost vaccines that may have helped prevent the kind of salmonella outbreak that has led to the recall of more than a half-billion eggs haven't been given to half of the nation's egg-laying hens.

The vaccines aren't required in the U.S., although in Great Britain, officials say vaccinations have given them the safest egg supply in Europe.

There's been no push to require vaccination in the U.S., in part because it would cost farmers and in part because advocates have been more focused on more comprehensive food safety reforms, those watching the poultry industry said.